Structure and ferroelectric properties of Bi_3.25La _0.75Ti₃O₁₂ and Bi_3.25Nd _0.75Ti₃O₁₂ thin films prepared by a MOD method

The structure and ferroelectric properties of Bi_3.25La _0.75Ti₃O₁₂ (BLT) and Bi_3.25Nd _0.75Ti₃O₁₂ (BNT) thin films deposited on (111)Pt/Ti/SiO₂/Si substrates using a metalorganic decomposition (MOD) method were investigated. Both the films were polycrystalline structure with the single bismuth-layered phase. The BNT film showed the (117) random orientation, while the BLT film displayed (00l)-preferential orientation. The BNT film showed a larger remnant polarization (∼13.8μ,C/cm²) than the BLT film (∼3.5μC/cm²), while both films displayed almost the same value of coercive field. The BNT film had the larger dielectric constant and a litter larger dissipation factor than the BLT film. The superior ferroelectricity of the BNT film was mainly attributed to its (117) random orientation. Furthermore, the BNT film displayed good fatigue endurance up to 10⁹ switching cycles, indicating it was a useful candidate for integrated device applications.